1. Field of the Invention
The present invention relates to a technique capable of recording data from a plurality of external apparatuses such as digital cameras on a recording medium.
2. Description of the Related Art
At present, removable media such as CF and SD cards are used to store image data captured by digital cameras. Removable media do not assume the use of a single removable medium for data read/write. A removable medium which becomes full of data must be inserted/removed into/from a dedicated slot in order to move data to another storage device such as a PC, bothering the user.
One memory card can exchange data with only one information device, and cannot exchange data with a plurality of information devices at the same time.
The memory card is thin and lightweight, and these physical restrictions limit the number of semiconductor memories mounted in the card. The limitation on the data save capacity of memory cards inhibits save of a large amount of data.
Since the memory card always uses a dedicated slot, it cannot be applied to a compact information device physically incapable of mounting a dedicated slot. External storage devices such as an external HDD, DVD, and CD-R/W have large data storage capacities, but are bulky, not easily portable, always require the AC power source, and are not suitable for mobile use.
In this situation, Japanese Patent Laid-Open No. 2003-78950 discloses a system capable of exchanging data between a portable remote storage and a plurality of devices such as a PDA, cell phone, and digital camera, and storing data in the portable remote storage.
However, when a plurality of digital cameras are connected to a portable remote storage, store shot images in the portable remote storage, and share one portable remote storage between them, the number of connected terminals changes dynamically. It is, therefore, convenient to share the data storage area.
According to this system, when a given digital camera shoots an image, the shared data storage area reduces and the number of shootable images of another connected digital camera decreases.
Thus, all connected digital cameras must periodically inquire, of the storage, the remaining area of the shared storage area or the number of shootable images. This puts a heavy burden on digital cameras and the portable remote storage.
If a plurality of digital cameras simultaneously request a shared portable remote storage to store image data, stored image data processed early consumes the shared data storage area. In response to this, the connected digital cameras are notified of the decrease in the number of shootable images. However, a digital camera for which the number of storable shot images becomes 0 has already completed shooting before the notification. In this case, a subsequent storage request results in an image data storage failure because of an insufficient storage area.
However, the conventional system does not consider the image data storage failure caused by the time lag between calculation and notification of the number of shootable images. This problem arises from sharing of the data storage area of a portable remote storage between a plurality of digital cameras.